AbstrakTujuan penelitian ini mendeskripsikan jenis dan faktor penyebab kesalahan siswa dalam menyelesaikan soal materi bilangan pecahan. Penelitian ini merupakan penelitian deskriptif. Subjek dalam penelitian ini adalah siswa Kelas VB SD Negeri 69 Kota Bengkulu sebanyak 32 orang. Instrumen dan teknik pengumpulan data yang digunakan dalam penelitian ini adalah lembar tes dan wawancara. Analisis data diawali dengan uji analisis instrumen tes, yaitu pengujian validitas, reliabilitas, tingkat kesukaran, daya pembeda soal dan analisis data hasil tes. Hasil penelitian menunjukkan bahwa kesalahan yang dilakukan siswa dalam menyelesaikan materi bilangan pecahan terdapat sebanyak lima indikator kesalahan. (1) Kesalahan dalam mengurutkan pecahan dengan tingkat kesalahan sebanyak 17 siswa (53,12%). (2) Kesalahan menyederhanakan pecahan sebanyak 5 siswa (15,62%). (3) Kesalahan menjumlahkan pecahan sebanyak 7 siswa (21,87%). (4) Kesalahan pengurangan pecahan sebanyak 17 siswa (53,12%). (5) Kesalahan dalam menyelesaikan masalah nyata yang berkaitan dengan pecahan sebanyak 10 siswa (31,25%). Faktor penyebab kesalahan siswa terdiri dari: (1) kurang memahami konsep materi, (2) kurang teliti dalam memahami soal; (4) kurang teliti dalam melakukan perhitungan, dan (4) tidak mengecek kembali jawaban akhir Kata Kunci: Analisis, Kesalahan, Deskriptif Abstract The aim of this research is for description kind of factor mistake from student about finish the test of lesson fraction number. The research is descriptive research. Subject of the research is Students Class 5 SD Negeri 69 Bengkulu city surely 32 Students. The technic of data collection from the research is essay and Ellyciting. Data analysis start from test instrumen analysis, That is, Validity test, reliability test, difficult level test, power of different the test, and data analysis results test. Results of the research can show about fault from the students finish the test of lesson the breakdown, that have 5 misconception of indicator from the students. (1) The fault about sort it out fraction number with level fault 17 student (53,12%). (2) The fault about simplicity the fraction number is five students (15,62%). (3) The fault about add up fractions number as much 7 The students (21,87%). (4) The fault of substraction fraction number as much 17 Students (53,12%). (5) The fault of solve a real problem deals the breakdown as much 10 students (31,25%). Factor the fault of students is have 5 factor, that is : (1) The students understandably the concept about the lesson, (2) The students less thoroughly about understand the test, (3) the student less thoroughly about do the math, and (4) the students does not checking in last answer. Keyword : Analysis, The Fault, Descriptive